import 'package:flutter/foundation.dart';

import '../../../shared/notifications/notification_service.dart';
import '../../../shared/network/api_client.dart';
import '../../../shared/storage/session_store.dart';
import '../domain/contract_models.dart';

class ContractGenerationController {
  ContractGenerationController({ApiClient? apiClient})
      : _apiClient = apiClient ?? const ApiClient();

  final ApiClient _apiClient;

  final ValueNotifier<bool> isPreviewing = ValueNotifier<bool>(false);
  final ValueNotifier<bool> isGenerating = ValueNotifier<bool>(false);
  final ValueNotifier<String?> errorMessage = ValueNotifier<String?>(null);
  final ValueNotifier<ContractPreviewItem?> preview =
      ValueNotifier<ContractPreviewItem?>(null);

  Future<void> loadPreview({
    required String templateId,
    required Map<String, String> variableValues,
  }) async {
    final session = SessionStore.current;
    if (session == null || !session.isAuthenticated) {
      errorMessage.value = '请先登录后预览合同';
      preview.value = null;
      return;
    }

    isPreviewing.value = true;
    errorMessage.value = null;
    try {
      preview.value = await _apiClient.previewContract(
        session.accessToken,
        templateId: templateId,
        variableValues: variableValues,
      );
    } on ApiException catch (error) {
      if (error.isUnauthorized) {
        await SessionStore.clear();
        errorMessage.value = '登录已过期，请重新登录';
      } else {
        errorMessage.value = error.message;
      }
      preview.value = null;
    } catch (_) {
      errorMessage.value = '合同预览失败，请稍后重试';
      preview.value = null;
    } finally {
      isPreviewing.value = false;
    }
  }

  Future<GeneratedContractItem> generate({
    required String templateId,
    required Map<String, String> variableValues,
    String exportFormat = 'docx',
  }) async {
    final session = SessionStore.current;
    if (session == null || !session.isAuthenticated) {
      throw const ContractGenerationException('请先登录后生成合同');
    }

    isGenerating.value = true;
    errorMessage.value = null;
    try {
      final contract = await _apiClient.generateContract(
        session.accessToken,
        templateId: templateId,
        variableValues: variableValues,
        exportFormat: exportFormat,
      );
      await NotificationService.instance.notifyContractGenerated(contract);
      return contract;
    } on ApiException catch (error) {
      if (error.isUnauthorized) {
        await SessionStore.clear();
        errorMessage.value = '登录已过期，请重新登录';
        throw const ContractGenerationException('登录已过期，请重新登录');
      }
      errorMessage.value = error.message;
      throw ContractGenerationException(error.message);
    } catch (_) {
      errorMessage.value = '合同生成失败，请稍后重试';
      throw const ContractGenerationException('合同生成失败，请稍后重试');
    } finally {
      isGenerating.value = false;
    }
  }

  void dispose() {
    isPreviewing.dispose();
    isGenerating.dispose();
    errorMessage.dispose();
    preview.dispose();
  }
}

class ContractGenerationException implements Exception {
  const ContractGenerationException(this.message);

  final String message;

  @override
  String toString() => message;
}